This invention relates generally to an outboard motor and, more particularly, to an arrangement for disposing an electric air control valve (hereinafter refereed to as xe2x80x9cEACVxe2x80x9d) interposed in an inlet system for the low-speed driving of the engine of an outboard motor.
An outboard motor is generally provided with an EACV serving as a control valve in an airflow control passageway of a throttle valve, for the engine driven at a low speed (hereinafter referred to as xe2x80x9cin low-speed drivingxe2x80x9d). An arrangement of this kind of EACV is disclosed in Japanese Patent Laid-Open Publication No. HEI-10-231761.
The body of the EACV is mounted in a direction orthogonal to the intake passage of a throttle body of a throttle valve. A solenoid valve attached to the EACV for varying the airflow rate in low-speed driving is provided in a direction orthogonal to a passageway of the EACV. It is thus necessary to leave a space for installing the EACV including the solenoid valve. Since the EACV is mounted to an intake manifold, the shape of the manifold determines the location of the EACV. This requires a large space in an engine space, making the engine space larger, and thus making an engine cover defining the contour of the outboard motor larger, resulting in an outboard motor of a larger size.
It may be conceived to integrally provide in the throttle valve, airflow control passageways constituting the EACV in low-speed driving. This, however, results in a complicated throttle valve structure, leading to significantly troublesome and complicated manufacturing and increased cost.
It may also be conceived to attach the EACV directly to the inlet manifold. In this case, however, the shape of the manifold determines the location of the EACV, being likely to undesirably affect the contour of the engine space. Further, it may be attempted to incorporate the EACV into the throttle valve. In this case, however, the shape of the throttle valve body determines the location of the EACV, causing problems as described above.
The present invention was made to solve the above problems and provides an outboard motor which allows an EACV to be disposed efficiently in a most-suitable position without putting restrictions on the space around a throttle valve and an intake manifold, thereby preventing an engine space from being enlarged.
According to an aspect of the present invention, there is provided an outboard motor, which comprises: an engine with a crankshaft disposed vertically; an engine cover surrounding the engine and the peripheral equipment, defining an engine space; an intake box for taking air in; a throttle valve with an intake passage, an upstream portion of the intake passage is connected to the intake box; an intake manifold connected to a downstream portion of the intake passage of the throttle valve; and a control valve fitted between a downstream portion of the intake passage of the throttle valve and an upstream portion of the intake manifold via a mounting member, for controlling airflow in low-speed driving of the engine, wherein the mounting member has a body with an intake passage and a supporter extending from the center of the intake passage to a desired position.
In the thus arranged outboard motor, an EACV as an airflow controlling passage device in low-speed driving of the engine is disposed between the downstream intake passageway of the throttle valve and the upstream intake passageway of the intake manifold connected to and communicating with the throttle valve. The position of the EACV is thus in the forward direction of the intake passageway without protruding circumferentially, thereby having a reduced length in the direction of the passageway between the throttle valve and the intake manifold. The supporter is disposed extending from the center of the intake passageway of the EACV, which prevents the outside shape of an intake system including the EACV from being enlarged. With the EACV installed, the engine space and the engine cover defining the engine space are prevented from being enlarged, thereby achieving the compact outside shape of the outboard motor determined by the engine cover. Further, since the EACV is not integrally provided to the throttle valve, which leads to the both devices having simplified structures.
The supporter supports a valve device for providing connection/disconnection between an input port opening into an upstream portion from a throttle plate of the throttle valve and an output port opening into a downstream portion from the throttle plate. In other words, the valve device such as a solenoid valve for connection/disconnection between the input port opening into the upstream portion from the throttle plate of the throttle valve and the output port opening into the downstream portion from the throttle plate is supported by the supporter of the body, so that such a valve as a solenoid valve can be provided without other supporting members being required. The valve device is preferably provided in a parallel relationship with an intake passageway formed in a throttle body.